The effects of spaceflight microgravity on the musculoskeletal system of humans and animals, with an emphasis on exercise as a countermeasure: a systematic scoping review.

The purpose of this systematic review is twofold: 1) to identify, evaluate, and synthesize the heretofore disparate scientific literatures regarding the effects of direct exposure to microgravity on the musculoskeletal system, taking into account for the first time both bone and muscle systems of both humans and animals; and 2) to investigate the efficacy and limitations of exercise countermeasures on the musculoskeletal system under microgravity in humans.The Framework for Scoping Studies (Arksey and O'Malley 2005) and the Cochrane Handbook for Systematic Reviews of Interventions (Higgins JPT 2011) were used to guide this review. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist was utilized in obtaining the combined results (Moher, Liberati et al. 2009). Data sources, PubMed, Embase, Scopus, and Web of Science were searched for published articles through October 2019 using the Mesh terms of microgravity, musculoskeletal system, and exercise countermeasures. A total of 84 references were selected, including 40 animal studies and 44 studies with human participants. The heterogeneity in the study designs, methodologies, and outcomes deemed this review unsuitable for a meta-analysis. Thus, we present a narrative synthesis of the results for the key domains under five categories: 1) Skeletal muscle responses to microgravity in humans 2) Skeletal muscle responses to microgravity in animals 3) Adaptation of the skeletal system to microgravity in humans 4) Adaptation of the skeletal system to microgravity in animals 5) Effectiveness of exercise countermeasures on the human musculoskeletal system in microgravity. Existing studies have produced only limited data on the combined effects on bone and muscle of human spaceflight, despite the likelihood that the effects on these two systems are complicated due to the components of the musculoskeletal system being anatomically and functionally interconnected. Bone is directly affected by muscle atrophy as well as by changes in muscle strength, notably at muscle attachments. Given this interplay, the most effective exercise countermeasure is likely to be robust, individualized, resistive exercise, primarily targeting muscle mass and strength.

An assessment of pulmonary function testing and ventilatory kinematics by optoelectronic plethysmography.

New advances in computer processing and imaging have allowed the development of innovative techniques to assess lung function. A promising methodology is optoelectronic plethysmography (OEP). OEP evaluates ventilatory kinematics through the use of infrared imaging. Markers are placed, and images read on the chest, back and abdomen of subjects. Currently, this system is used mainly in research settings, but in the future may have broad applicability to patient populations such as very young children, patients with neuromuscular disease and patients who cannot be tested with classical spirometry testing. This paper presents the history and development of OEP, along with a summary of the OEP methodology, a discussion of research findings and results to date, as well as application and limitations.

Physical activity staging distribution: establishing a heuristic using multiple studies.

The purpose of this study was to identify the population prevalence across the stages of change (SoC) for regular physical activity and to establish the prevalence of people at risk. With support from the National Institutes of Health, the American Heart Association, and the Robert Wood Johnson Foundation, nine Behavior Change Consortium studies with a common physical activity SoC measure agreed to collaborate and share data. The distribution pattern identified in these predominantly reactively recruited studies was Precontemplation (PC) = 5% (+/- 10), Contemplation (C) = 10% (+/- 10), Preparation (P) = 40% (+/- 10), Action = 10% (+/- 10), and Maintenance = 35% (+/- 10). With reactively recruited studies, it can be anticipated that there will be a higher percentage of the sample that is ready to change and a greater percentage of currently active people compared to random representative samples. The at-risk stage distribution (i.e., those not at criteria or PC, C, and P) was approximately 10% PC, 20% C, and 70% P in specific samples and approximately 20% PC, 10% C, and 70% P in the clinical samples. Knowing SoC heuristics can inform public health practitioners and policymakers about the population's motivation for physical activity, help track changes over time, and assist in the allocation of resources.

Effects of a community-based intervention on physical activity: the Pawtucket Heart Health Program.

OBJECTIVES: The effect of a community-based physical activity program in Pawtucket, RI, was evaluated relative to one in a comparison community. METHODS: Cross-sectional surveys of 7529 residents of Pawtucket, RI, and 7732 residents of the comparison city were conducted at 2-year intervals during 7 years of intervention. RESULTS: There were no differences in self-reported knowledge of the benefits of physical activity, attempts to increase exercise, or prevalence of physical inactivity between Pawtucket and the comparison community. CONCLUSIONS: Future community-based physical activity interventions should attempt to involve a wider range of individuals.

Emergency department use of aspirin in patients with possible acute myocardial infarction.

BACKGROUND: Efforts have been made to improve the suboptimal use of aspirin after hospitalization. OBJECTIVE: To assess the frequency and timing of aspirin administration in emergency department patients with possible myocardial infarction. DESIGN: Retrospective record review. SETTING: Emergency departments of four hospitals affiliated with the same university. PATIENTS: All patients who were admitted to the four hospitals in 1994 for evaluation and treatment of suspected acute myocardial infarction. MEASUREMENTS: The frequency and timing of aspirin administration and the definitive diagnosis established before discharge from the hospital. RESULTS: Aspirin was not given to 253 of 463 emergency department patients (55%) who had a definitive diagnosis of acute myocardial infarction. Seventy-eight percent of patients who did receive aspirin received it more than 30 minutes after arrival in the emergency department. CONCLUSION: Aspirin therapy is underutilized as the first intervention in patients who are admitted with suspected myocardial infarction.

Protein kinase A downregulates the phosphorylation of p47 phox in human neutrophils: a possible pathway for inhibition of the respiratory burst.

Cyclic adenosine monophosphate (cAMP)-dependent protein kinase A(PKA) is considered to be a physiologic modulator of superoxide generation by stimulated neutrophils. Mechanisms of the inhibitory action of PKA are poorly understood. In this study, we investigated effects of cAMP-elevating agents on the phosphorylation of p47 phox in human neutrophils stimulated with the chemotactic peptide fMet-Leu-Phe (fMLP). We observed that the fMLP-induced phosphorylation of p47 phox, an essential component of neutrophil NADPH oxidase, was significantly attenuated in the presence of dibutyryl-cAMP or of receptor agonists of adenylate cyclase. This attenuation was reversed in the presence of 0.4 microM KT 5720, a selective inhibitor of PKA. The effects of cAMP agonists and of KT 5720 on the phosphorylation of p47 phox were paralleled by similar effects on superoxide generation. In neutrophils stimulated with phorbol myristate acetate (PMA), which directly activates protein kinase C (PKC), neither cAMP agonists nor dibutyryl cAMP exerted any effects on p47 phox phosphorylation or superoxide generation. These results indicated that the PKA-dependent downregulation of fMLP-induced p47 phox phosphorylation apparently involves step(s) in the fMLP-signaling pathway that are upstream of PKC. The inhibition demonstrated here of p47 phox phosphorylation by cAMP agonists may underlie a physiologically significant mechanism whereby cAMP modulates the receptor-mediated respiratory burst in neutrophils.

Sedentary lifestyle and risk of coronary heart disease in women.

Relatively few studies have assessed the prospective relationship of sedentary lifestyle and coronary heart disease (CHD) in women. We performed a nested case-control study, identifying 50 cases of acute CHD in women and 150 age-matched controls. Risk factors including sedentary lifestyle, cigarette smoking, hypertension, diabetes mellitus, total, and HDL cholesterol levels had been previously determined in this cohort using household survey techniques. The odds ratio (OR) of CHD in sedentary women was 2.1 (95% CI 1.0-4.3, P = 0.046). The odds ratio was similar (OR = 2.3, 95% CI 1.0-5.7, P = 0.051) after adjusting for potential confounders of hypertension, cigarette smoking, low HDL cholesterol, diabetes mellitus, and being U.S. born. This study suggests that sedentary lifestyle may be an independent risk factor for CHD in women, but its results are open to several contradictory interpretations. Further studies to investigate the prospective relationship of sedentary lifestyle and the risk of CHD in women are needed.

Involvement of protein kinase C and of protein phosphatases 1 and/or 2A in p47 phox phosphorylation in formylmet-Leu-Phe stimulated neutrophils: studies with selective inhibitors RO 31-8220 and calyculin A.

Previously employed non-selective protein kinase inhibitors yielded inconclusive results regarding involvement of protein kinase C (PKC) in phosphorylation of 47 kDa protein (p47 phox) in intact neutrophils stimulated with physiologic agonists of superoxide generation. In the present study, phosphorylation of p47 phox in formylMet-Leu-Phe (fMLP) stimulated neutrophils was potently inhibited in the presence of 0.3 microM RO 31-8220, a selective inhibitor of PKC. These results provide experimental evidence in support of the currently considered essential involvement of PKC in p47 phox phosphorylation in response to physiologic stimulation of neutrophil surface receptors. The fMLP-induced phosphorylation of p47 phox was enhanced and prolonged by calyculin A, a specific inhibitor of protein phosphatases of types 1 and 2A, and such enhanced phosphorylation was also effectively inhibited by RO 31-8220. Our results suggest that the extent and duration of p47 phox phosphorylation in intact fMLP-stimulated neutrophils is probably controlled by a balance between the activities of PKC, on the one hand, and of protein phosphatase(s) of type(s) 1 and/or 2A, on the other. Effects of RO 31-8220 and of calyculin A on the fMLP-induced p47 phox phosphorylation were paralleled by similar effects on superoxide release. Calyculin A and RO 31-8220 were also used to study signal transduction by a post-receptor agonist of superoxide generation, a calcium ionophore A23187. The results of the latter study indicated that PKC was activated in A23187-stimulated neutrophils and was essentially involved in superoxide generation and p47 phox phosphorylation. Further, these results suggested that protein phosphatase(s) of type(s) 1 and/or 2A were also activated in A23187-signalling pathway, and limited the extent of superoxide release and p47 phox phosphorylation.

A comparison of exercise performance on bicycle and rowing ergometers in female master recreational rowers.

Limited information exists on the response to maximal exercise testing in female masters level recreational rowers. This study examined cardiorespiratory and physiologic responses to progressive, incremental exercise using a variable resistance rowing ergometer and a cycle ergometer in six experienced female masters level rowers. Maximal oxygen uptake (VO2 max:33.8 +/- 7.3, 33.5 +/- 6.6 ml.kg-1.min-1) and minute ventilation (VEmax: 86.1 +/- 9.6 l.min-1, 88.7 +/- 13.8 l.min-1) were similar during both tests (rower vs cycle). Maximal heart rates were significantly higher on the cycle ergometer (177 +/- 9 beats/min-1) compared to the rowing ergometer (173 +/- 11 beats/min-1), while peak power on the rowing ergometer (175 +/- 22 watts) was lower than the cycle ergometer (187 +/- 41 watts). Blood lactate levels taken 1 minute following exercise were similar on the rowing ergometer (10.5 +/- 1.7 mM/l) and cycle ergometer (11.8 +/- 1.5 mM/l) and indicated maximal effort was achieved in all subjects. Ventilatory threshold levels were significantly different on the rower (2.0 +/- 0.16) versus the cycle ergometer (1.9 +/- 0.18) (p = 0.38). These data suggest that the cycle and rowing ergometers yield relatively similar results when testing maximal exercise performance in this population.

Cross-sectional relationship between diet and physical activity in two southeastern New England communities.

The hypothesis that health promotive diets associated with higher levels of habitual physical activity confound the relationship between regular physical activity and health has not been well explored in epidemiologic studies. We evaluated self-reported physical activity, Willett Food Frequency dietary data, sociodemographic and physiologic factors cross-sectionally for 2,004 household survey participants in two southeastern New England communities. We compared the dietary habits of sedentary participants (n = 964) to those of moderately active (n = 600) and very active (n = 440) participants after adjusting for age, gender, education, smoking status, year of survey, and total calories. Our results showed that moderately active and very active participants consumed more fiber, less total fat, and less saturated fat than sedentary participants (P < .01). They also consumed more vitamins (A, C, D, E), beta carotene, and calcium, (P < .01), and ate more fruits and vegetables (P < .001) than sedentary participants. We found these relationships in both New England communities studied. This association between regular physical activity and diet suggests that the relationship of habitual physical activity and chronic disease may be confounded by diet.

Physical activity, physical fitness, and coronary heart disease risk factors.

The relationships between physical activity, physical fitness, and coronary heart disease risk factors measured in a large community sample were evaluated. Self-reported physical activity using a single question, maximal oxygen consumption estimates derived from the Pawtucket Heart Health Step Test, blood pressure, nonfasting lipids, and body mass index were cross-sectionally evaluated in 381 men and 556 women. The correlation of estimated maximal oxygen consumption and self-reported physical activity was modest but statistically significant (r = 0.13 in men and r = 0.19 in women). Blood pressure, body mass index, and HDL cholesterol were correlated with physical fitness (r = 0.24-0.65) and correlated to self-reported physical activity (r = 0.09-0.14). Evaluation of coronary heart disease risk factors using both physical activity and physical fitness revealed a complex relationship that generally showed a stronger relationship with measures of physical fitness than with physical activity. This study suggests that simultaneous measurement of physical activity and physical fitness may be useful in epidemiologic studies of habitual physical activity and chronic disease.

Developing a competency-based preventive medicine curriculum for medical schools.

Trends in patient morbidity and mortality, cost-effectiveness, and national recommendations mandate that we practice more preventive medicine. To address this need, we set out to develop a comprehensive curriculum in preventive medicine for medical schools. We constructed a competency-based (i.e., performance-based) curriculum with specific educational objectives defined by outcomes. Subject areas were subdivided by life stages, and learning objectives were created separately for epidemiology, assessment, and intervention. We hope that adoption of such an educational blueprint by medical schools will measurably enhance the attitudes, knowledge, and skills necessary for the incorporation of preventive principles into all aspects of clinical medicine.

Coronary care unit requirements of patients with acute myocardial infarction treated with or without thrombolytic therapy: a pilot study.

OBJECTIVE: To determine if patients with acute myocardial infarction who receive thrombolytic therapy require more nursing care hours and a longer length of stay in the coronary care unit than those patients with acute myocardial infarction who do not receive thrombolytic therapy. DESIGN: Retrospective cohort study using the coronary care unit data base and patient classification records. SETTING: Northeastern university-affiliated, community-based, cardiovascular tertiary care center. PATIENTS: All patients admitted to the coronary care unit with a diagnosis of acute myocardial infarction were screened. Of these, 20 patients who also had a patient classification form completed were included in the study. Ten of these patients had received thrombolytic therapy and 10 had not. The patients were grouped according to treatment with a thrombolytic agent or conventional treatment. There was no significant difference in age between the groups (64 +/- 19 years and 67 +/- 15 years). OUTCOME MEASURES: Nursing care hours per patient per day and length of stay per patient in the coronary care unit. RESULTS: On days 1 and 2 of hospitalization, there were no significant differences in total nursing care hours provided per patient per day. On days 3 and 4, those patients who received thrombolytic therapy received fewer nursing care hours compared with those who did not (11.1 and 9.2 vs 13.8 and 12.7 hours per patient day, respectively; p < or = 0.05). Patients who were treated with thrombolytic therapy also had a significantly shorter coronary care unit stay (3.1 vs 4.0 days; p < or = 0.05). CONCLUSION: In this retrospective, observational pilot study, patients who received thrombolytic therapy for treatment of acute myocardial infarction had a significantly shorter coronary care unit stay and required significantly less nursing care on days 3 and 4.